Signatures of Primordial non-Gaussianities in the Matter Power-Spectrum and Bispectrum: the Time-RG Approach

TL;DR

This paper uses the time-RG approach to analyze how primordial non-Gaussianities influence the non-linear evolution of matter power spectra and bispectra, providing accurate predictions aligned with N-body simulations.

Contribution

It introduces a novel application of the time-RG method to primordial non-Gaussianities, improving predictions of matter spectra and bispectra for different non-Gaussian shapes.

Findings

Accurately fits N-body data for local non-Gaussianity up to k ~ 0.25 h/Mpc at z=0.

Provides predictions for matter bispectra for various non-Gaussian shapes.

Analyzes running non-Gaussianity with momentum-dependent f_NL.

Abstract

We apply the time-renormalization group approach to study the effect of primordial non-Gaussianities in the non-linear evolution of cosmological dark matter density perturbations. This method improves the standard perturbation approach by solving renormalization group-like equations governing the dynamics of gravitational instability. The primordial bispectra constructed from the dark matter density contrast and the velocity fields represent initial conditions for the renormalization group flow. We consider local, equilateral and folded shapes for the initial non-Gaussianity and analyze as well the case in which the non-linear parameter f_{NL} parametrizing the strength of the non-Gaussianity depends on the momenta in Fourier space through a power-law relation, the so-called running non-Gaussianity. For the local model of non-Gaussianity we compare our findings for the power-spectrum with those of recent N-body simulations and find that they accurately fit the N-body data up to wave-numbers k \sim 0.25 h/Mpc at z=0. We also present predictions for the (reduced) matter bispectra for the various shapes of non-Gaussianity.